Phenolic compounds, particularly hydroxyphenyl substituted isocyanurate compounds, are known to be stabilizers for organic materials (see U.S. Pat. Nos. 3,531,483 and 3,637,582). Phosphorous-containing compounds, particularly phosphites and pentaerythritol phosphites, are also known to be stabilizers for organic materials (see U.S. Pat. Nos. 2,847,443; 3,053,878; 3,205,250; 3,293,327; 3,310,609; and 3,737,485). Specific combinations of phenolic compounds and phosphorous-containing compounds are also disclosed in the art. Relevant art in this area is: U.S. Pat. Nos. 3,112,272; 3,115,466; 3,145,176; 3,294,736; 3,333,027; 3,462,375; 3,567,724; 3,652,561; 3,678,047; and 3,886,114; British Pat. Nos. 1,380,449 and 1,320,169.